Compound eccentric mechanism



6, 1932. c, COOPER 1,875,854

COMPOUND EGCENIBIC MECHANISM Filed Dec. 21, 1931 Patented Sept. 6, 1932UNITED STATES, PATENTl-QFFICET GEORGE CECIL ooornn, OF'LONDON, ENGLnNpCOMPOUND EooENrR Io MECHANISM Application filed December 21, 1931,Serial No. 582,403, and in Great l3ritain January 20, 1931. 7

This invention relates to improvements in compound eccentric mechanism,particularly applicable for use in vibrating a screening or othersurface, or for other purposes in which an adjustable Variation in areciproeating motion or travel is of service.

In mechanism employing the variable motion derivable from a compoundeccentric,

A it has been proposed to vary the eccentricity of a pair of eccentrics,mounted one over the other on a revolving shaft, by means whereby theone eccentric may be moved angularly with respect to the other eccentricwhilst the shaft is revolving.

The objects of the present invention are to reduce the number of workingparts, produce a more compact, reliable, efficient and positivemechanism, reduce the cost of manufacture and generally improve suchmecha- The present invention comprises a pair of co-axially arrangedeccentrics, both of which are splined, keyed or otherwise arranged torotate with a driving shaft, the one eccentric is fixed to the shaft andthe other eccentric is free to be moved axially thereon, an outereccentric mounted on and free to be rotated on the pair of co-axiallyarranged inner eecentrics, a strap or its equivalent on the "outereccentric for transmitting the desired motion and means for angularlymoving the outer eccentric with respect to the inner pair of eccentricsconsisting in the provision of H a stud or studs on the one eccentricadapted to be engaged by a helical slot or slots in the other eccentric,and means for axially sliding the axially movable eccentric.

This invention will be now more particuularly described making referenceto the accompanying drawing in which Fig. 1 is a part view in sideelevationpartly in section-of one embodiment of this invention.

Fig. 2 is a View in transverse section on line 'II-II of Fig. 1, and 1Fig. 3 is an enlarged diagram showing the centres of shaft and innereccentric and path of travel of outer eccentric and centres 50. of thelatter in two difierent positions.

Throughout .the views similar parts are" marked with like "letters ofreference.

A driving shaft a the axis. of which is designated a is mounted to berevolved in suitable bearings carried'by a frame ac. OIi this shaft a issplined a pair of co-axially. arranged eccentrics b, 0, the commoncentre of whichis' designatedb The one eccentric bis fixed tothedrivingshaft a so as to rotate' therewithin any convenient way, for instance bya key b and setiscrewb. The othertec centric o is free to slide axiallyon the shaft a but to frotate therewith, a convenient arrangement beingto fix akeyLa onithe shaft to engage a,,'lsiey way'o inthe boreoflthepiart c. the pair of inner eccentrics I), c, 'and.free torotatethereon is mounted an outer eccentric (Lthe: centre of" which isdesignated 03 rotating round the, centre 6 QA strap e. is carried in abearing on the outer eccentric d. andis furnished with a rod 6 which isconnected to the vi-. brating screenor other mechanism in which anadjustable reciprocating motion or travel is of service, cap or collar 6retains the strap 6 in position. Angular movement of, the outer.eccentric d relative to the inner eccentrics b, a, isprovided by meansof studs or keys ti? projecting :within the bore of the outer eccentricdand adapted to .engagehelical slots c pcut in the surface of theeccentric 0 In some cases, the studs might be carried by the eccentricc, in vwhich case the slots 0, would be cutin the bore of theouterecce'na tric d. In the diagram, Fig. 3, which shows 7 the amountofvariation'of travel or rangeoi' adjustment possible with theconstruction shown, a designates the 'centreof thefdriw' ing shaft, 6the centre ofthe inner eccentrics b, 0, andthe path of the outereccentric dis. designatedd p It will' be understood that if the pair ofinner eccentrics b c and the outer eccentric d be given the same amountofeccentricity, it is lpossible, with helicalgrooves extending round theone part, to secure any. required throw of the :compound ,eccentric fromnil to maximum.

Any suitable 'mechanismmay' be employed 109 lar 0 is adapted to beengaged a ng d to move the eccentric c axially with respect to the shafta. In the construction shown, the outer end of the eccentric c is fixedto or made in one with an extension a forming a collar concentric withthe shaft a. This colby pins 7 carried by a forked bracket P, the upperend of which is provided with a nut or screwed sleeve f which is engagedby a screw thread 9 formed ona rotatable shaft 9 The forked bracket 7 iscarried by fixed guide rods h carried by brackets h fixed on the frame wand is moved thereon so as to impart axial action to the eccentric c byouter eccentric mounted on and-free to be rotated on the pair ofco-axially arranged inner eccentrics, a strap on the outer eccentric fortransmitting the desired motion, and 7 means for angularly moving theouter eccentric with respect to the inner pair of eccentrics consistingof a helical sloton the one eccentric, a'stud on the other eccentricengaging said helical slot, and screw mechanism for axially sliding theaxially movable eccentric of the pair ofco-axially arranged eccentrics.

' GEORGE- CECIL COOPER.

rotating the shaft 9 by means, of a hand wheel 9 V From the aboveconstruction, it will be seen that as the mechanism employed to vary theeccentricity of he compound eccentric rotates concentrically with theinner eccen-v tric, the whole gear revolves as a solid unitin anyposition, all relative motion being avoided between the driving anddriven points of contact, which is not possible in previousconstructions of mechanism employed in varying the eccentricity of acompound eccentric. .7 V

' I, declare that what I claim and desire to secure by Letters Patentis:- v 1. Compound. eccentric mechanism comprising a driving shaft,apair of co-axially arrangedeccentrics, splined to, rotate with saidshaft, one eccentric being" fixed to and the other. eccentric.

being free tomove axially on said shaft, an outer eccentric mounted onand free to be both of which are rotated on the pair of co-axially'arranged.

inner eccentrics, a strap on tric for transmitting the desired motion,

the outer eccenand ! means for angularly moving the outer eccentricwithrespect to the inner pair of eccentries. .7

.2. Compound eccentric mechanism comprising a driving shaft, a pair. ofco-axially eccentrics to rotate withsaid shaft,'one eccentric beingfixed to and the'other eccentric being. free to move axially on saidshaft, an outer eccen-- tric mounted on and free to be rotatedon thepairof co-axially arranged inner eccen tries, a strap on the outereccentric for transmitting the desired motion, and means for angularlymoving the outerveccentric' with respect to the inner pairof eccentricscons sistlng of a I helical slot on the one eccentric, a Stand on theother eccentric'engaging said helical slot and means for axially'slidingthe axially. movable eccentric of the pair of: co-axially arrangedeccentrics. g m a 3. Compound eccentric mechanism come,

prisinga driving shaft, a pair of co-axially arranged eccentrics, bothof which are splined to rotatewith saidshaft, one eccena tric beingfixed to and the other eccentric being free .to move axially on saidshaft, an

both of which are splined I no

